mudgangster

lparser.cc (46319B)

---

 /*
 ** $Id: lparser.c,v 2.155.1.2 2017/04/29 18:11:40 roberto Exp $
 ** Lua Parser
 ** See Copyright Notice in lua.h
 */
 
 #define lparser_c
 #define LUA_CORE
 
 #include "lprefix.h"
 
 
 #include <string.h>
 
 #include "lua.h"
 
 #include "lcode.h"
 #include "ldebug.h"
 #include "ldo.h"
 #include "lfunc.h"
 #include "llex.h"
 #include "lmem.h"
 #include "lobject.h"
 #include "lopcodes.h"
 #include "lparser.h"
 #include "lstate.h"
 #include "lstring.h"
 #include "ltable.h"
 
 
 
 /* maximum number of local variables per function (must be smaller
    than 250, due to the bytecode format) */
 #define MAXVARS		200
 
 
 #define hasmultret(k)		((k) == VCALL || (k) == VVARARG)
 
 
 /* because all strings are unified by the scanner, the parser
    can use pointer equality for string equality */
 #define eqstr(a,b)	((a) == (b))
 
 
 /*
 ** nodes for block list (list of active blocks)
 */
 typedef struct BlockCnt {
   struct BlockCnt *previous;  /* chain */
   int firstlabel;  /* index of first label in this block */
   int firstgoto;  /* index of first pending goto in this block */
   lu_byte nactvar;  /* # active locals outside the block */
   lu_byte upval;  /* true if some variable in the block is an upvalue */
   lu_byte isloop;  /* true if 'block' is a loop */
 } BlockCnt;
 
 
 
 /*
 ** prototypes for recursive non-terminal functions
 */
 static void statement (LexState *ls);
 static void expr (LexState *ls, expdesc *v);
 
 
 /* semantic error */
 static l_noret semerror (LexState *ls, const char *msg) {
   ls->t.token = 0;  /* remove "near <token>" from final message */
   luaX_syntaxerror(ls, msg);
 }
 
 
 static l_noret error_expected (LexState *ls, int token) {
   luaX_syntaxerror(ls,
       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
 }
 
 
 static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
   lua_State *L = fs->ls->L;
   const char *msg;
   int line = fs->f->linedefined;
   const char *where = (line == 0)
                       ? "main function"
                       : luaO_pushfstring(L, "function at line %d", line);
   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
                              what, limit, where);
   luaX_syntaxerror(fs->ls, msg);
 }
 
 
 static void checklimit (FuncState *fs, int v, int l, const char *what) {
   if (v > l) errorlimit(fs, l, what);
 }
 
 
 static int testnext (LexState *ls, int c) {
   if (ls->t.token == c) {
     luaX_next(ls);
     return 1;
   }
   else return 0;
 }
 
 
 static void check (LexState *ls, int c) {
   if (ls->t.token != c)
     error_expected(ls, c);
 }
 
 
 static void checknext (LexState *ls, int c) {
   check(ls, c);
   luaX_next(ls);
 }
 
 
 #define check_condition(ls,c,msg)	{ if (!(c)) luaX_syntaxerror(ls, msg); }
 
 
 
 static void check_match (LexState *ls, int what, int who, int where) {
   if (!testnext(ls, what)) {
     if (where == ls->linenumber)
       error_expected(ls, what);
     else {
       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
              "%s expected (to close %s at line %d)",
               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
     }
   }
 }
 
 
 static TString *str_checkname (LexState *ls) {
   TString *ts;
   check(ls, TK_NAME);
   ts = ls->t.seminfo.ts;
   luaX_next(ls);
   return ts;
 }
 
 
 static void init_exp (expdesc *e, expkind k, int i) {
   e->f = e->t = NO_JUMP;
   e->k = k;
   e->u.info = i;
 }
 
 
 static void codestring (LexState *ls, expdesc *e, TString *s) {
   init_exp(e, VK, luaK_stringK(ls->fs, s));
 }
 
 
 static void checkname (LexState *ls, expdesc *e) {
   codestring(ls, e, str_checkname(ls));
 }
 
 
 static int registerlocalvar (LexState *ls, TString *varname) {
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
   int oldsize = f->sizelocvars;
   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
                   LocVar, SHRT_MAX, "local variables");
   while (oldsize < f->sizelocvars)
     f->locvars[oldsize++].varname = NULL;
   f->locvars[fs->nlocvars].varname = varname;
   luaC_objbarrier(ls->L, f, varname);
   return fs->nlocvars++;
 }
 
 
 static void new_localvar (LexState *ls, TString *name) {
   FuncState *fs = ls->fs;
   Dyndata *dyd = ls->dyd;
   int reg = registerlocalvar(ls, name);
   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
                   MAXVARS, "local variables");
   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
 }
 
 
 static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
   new_localvar(ls, luaX_newstring(ls, name, sz));
 }
 
 #define new_localvarliteral(ls,v) \
 	new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
 
 
 static LocVar *getlocvar (FuncState *fs, int i) {
   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
   lua_assert(idx < fs->nlocvars);
   return &fs->f->locvars[idx];
 }
 
 
 static void adjustlocalvars (LexState *ls, int nvars) {
   FuncState *fs = ls->fs;
   fs->nactvar = cast_byte(fs->nactvar + nvars);
   for (; nvars; nvars--) {
     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
   }
 }
 
 
 static void removevars (FuncState *fs, int tolevel) {
   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
   while (fs->nactvar > tolevel)
     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
 }
 
 
 static int searchupvalue (FuncState *fs, TString *name) {
   int i;
   Upvaldesc *up = fs->f->upvalues;
   for (i = 0; i < fs->nups; i++) {
     if (eqstr(up[i].name, name)) return i;
   }
   return -1;  /* not found */
 }
 
 
 static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
   Proto *f = fs->f;
   int oldsize = f->sizeupvalues;
   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
                   Upvaldesc, MAXUPVAL, "upvalues");
   while (oldsize < f->sizeupvalues)
     f->upvalues[oldsize++].name = NULL;
   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
   f->upvalues[fs->nups].name = name;
   luaC_objbarrier(fs->ls->L, f, name);
   return fs->nups++;
 }
 
 
 static int searchvar (FuncState *fs, TString *n) {
   int i;
   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
     if (eqstr(n, getlocvar(fs, i)->varname))
       return i;
   }
   return -1;  /* not found */
 }
 
 
 /*
   Mark block where variable at given level was defined
   (to emit close instructions later).
 */
 static void markupval (FuncState *fs, int level) {
   BlockCnt *bl = fs->bl;
   while (bl->nactvar > level)
     bl = bl->previous;
   bl->upval = 1;
 }
 
 
 /*
   Find variable with given name 'n'. If it is an upvalue, add this
   upvalue into all intermediate functions.
 */
 static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
   if (fs == NULL)  /* no more levels? */
     init_exp(var, VVOID, 0);  /* default is global */
   else {
     int v = searchvar(fs, n);  /* look up locals at current level */
     if (v >= 0) {  /* found? */
       init_exp(var, VLOCAL, v);  /* variable is local */
       if (!base)
         markupval(fs, v);  /* local will be used as an upval */
     }
     else {  /* not found as local at current level; try upvalues */
       int idx = searchupvalue(fs, n);  /* try existing upvalues */
       if (idx < 0) {  /* not found? */
         singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
         if (var->k == VVOID)  /* not found? */
           return;  /* it is a global */
         /* else was LOCAL or UPVAL */
         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
       }
       init_exp(var, VUPVAL, idx);  /* new or old upvalue */
     }
   }
 }
 
 
 static void singlevar (LexState *ls, expdesc *var) {
   TString *varname = str_checkname(ls);
   FuncState *fs = ls->fs;
   singlevaraux(fs, varname, var, 1);
   if (var->k == VVOID) {  /* global name? */
     expdesc key;
     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
     lua_assert(var->k != VVOID);  /* this one must exist */
     codestring(ls, &key, varname);  /* key is variable name */
     luaK_indexed(fs, var, &key);  /* env[varname] */
   }
 }
 
 
 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
   FuncState *fs = ls->fs;
   int extra = nvars - nexps;
   if (hasmultret(e->k)) {
     extra++;  /* includes call itself */
     if (extra < 0) extra = 0;
     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
     if (extra > 1) luaK_reserveregs(fs, extra-1);
   }
   else {
     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
     if (extra > 0) {
       int reg = fs->freereg;
       luaK_reserveregs(fs, extra);
       luaK_nil(fs, reg, extra);
     }
   }
   if (nexps > nvars)
     ls->fs->freereg -= nexps - nvars;  /* remove extra values */
 }
 
 
 static void enterlevel (LexState *ls) {
   lua_State *L = ls->L;
   ++L->nCcalls;
   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
 }
 
 
 #define leavelevel(ls)	((ls)->L->nCcalls--)
 
 
 static void closegoto (LexState *ls, int g, Labeldesc *label) {
   int i;
   FuncState *fs = ls->fs;
   Labellist *gl = &ls->dyd->gt;
   Labeldesc *gt = &gl->arr[g];
   lua_assert(eqstr(gt->name, label->name));
   if (gt->nactvar < label->nactvar) {
     TString *vname = getlocvar(fs, gt->nactvar)->varname;
     const char *msg = luaO_pushfstring(ls->L,
       "<goto %s> at line %d jumps into the scope of local '%s'",
       getstr(gt->name), gt->line, getstr(vname));
     semerror(ls, msg);
   }
   luaK_patchlist(fs, gt->pc, label->pc);
   /* remove goto from pending list */
   for (i = g; i < gl->n - 1; i++)
     gl->arr[i] = gl->arr[i + 1];
   gl->n--;
 }
 
 
 /*
 ** try to close a goto with existing labels; this solves backward jumps
 */
 static int findlabel (LexState *ls, int g) {
   int i;
   BlockCnt *bl = ls->fs->bl;
   Dyndata *dyd = ls->dyd;
   Labeldesc *gt = &dyd->gt.arr[g];
   /* check labels in current block for a match */
   for (i = bl->firstlabel; i < dyd->label.n; i++) {
     Labeldesc *lb = &dyd->label.arr[i];
     if (eqstr(lb->name, gt->name)) {  /* correct label? */
       if (gt->nactvar > lb->nactvar &&
           (bl->upval || dyd->label.n > bl->firstlabel))
         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
       closegoto(ls, g, lb);  /* close it */
       return 1;
     }
   }
   return 0;  /* label not found; cannot close goto */
 }
 
 
 static int newlabelentry (LexState *ls, Labellist *l, TString *name,
                           int line, int pc) {
   int n = l->n;
   luaM_growvector(ls->L, l->arr, n, l->size,
                   Labeldesc, SHRT_MAX, "labels/gotos");
   l->arr[n].name = name;
   l->arr[n].line = line;
   l->arr[n].nactvar = ls->fs->nactvar;
   l->arr[n].pc = pc;
   l->n = n + 1;
   return n;
 }
 
 
 /*
 ** check whether new label 'lb' matches any pending gotos in current
 ** block; solves forward jumps
 */
 static void findgotos (LexState *ls, Labeldesc *lb) {
   Labellist *gl = &ls->dyd->gt;
   int i = ls->fs->bl->firstgoto;
   while (i < gl->n) {
     if (eqstr(gl->arr[i].name, lb->name))
       closegoto(ls, i, lb);
     else
       i++;
   }
 }
 
 
 /*
 ** export pending gotos to outer level, to check them against
 ** outer labels; if the block being exited has upvalues, and
 ** the goto exits the scope of any variable (which can be the
 ** upvalue), close those variables being exited.
 */
 static void movegotosout (FuncState *fs, BlockCnt *bl) {
   int i = bl->firstgoto;
   Labellist *gl = &fs->ls->dyd->gt;
   /* correct pending gotos to current block and try to close it
      with visible labels */
   while (i < gl->n) {
     Labeldesc *gt = &gl->arr[i];
     if (gt->nactvar > bl->nactvar) {
       if (bl->upval)
         luaK_patchclose(fs, gt->pc, bl->nactvar);
       gt->nactvar = bl->nactvar;
     }
     if (!findlabel(fs->ls, i))
       i++;  /* move to next one */
   }
 }
 
 
 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
   bl->isloop = isloop;
   bl->nactvar = fs->nactvar;
   bl->firstlabel = fs->ls->dyd->label.n;
   bl->firstgoto = fs->ls->dyd->gt.n;
   bl->upval = 0;
   bl->previous = fs->bl;
   fs->bl = bl;
   lua_assert(fs->freereg == fs->nactvar);
 }
 
 
 /*
 ** create a label named 'break' to resolve break statements
 */
 static void breaklabel (LexState *ls) {
   TString *n = luaS_new(ls->L, "break");
   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
   findgotos(ls, &ls->dyd->label.arr[l]);
 }
 
 /*
 ** generates an error for an undefined 'goto'; choose appropriate
 ** message when label name is a reserved word (which can only be 'break')
 */
 static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
   const char *msg = isreserved(gt->name)
                     ? "<%s> at line %d not inside a loop"
                     : "no visible label '%s' for <goto> at line %d";
   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
   semerror(ls, msg);
 }
 
 
 static void leaveblock (FuncState *fs) {
   BlockCnt *bl = fs->bl;
   LexState *ls = fs->ls;
   if (bl->previous && bl->upval) {
     /* create a 'jump to here' to close upvalues */
     int j = luaK_jump(fs);
     luaK_patchclose(fs, j, bl->nactvar);
     luaK_patchtohere(fs, j);
   }
   if (bl->isloop)
     breaklabel(ls);  /* close pending breaks */
   fs->bl = bl->previous;
   removevars(fs, bl->nactvar);
   lua_assert(bl->nactvar == fs->nactvar);
   fs->freereg = fs->nactvar;  /* free registers */
   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
   if (bl->previous)  /* inner block? */
     movegotosout(fs, bl);  /* update pending gotos to outer block */
   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
 }
 
 
 /*
 ** adds a new prototype into list of prototypes
 */
 static Proto *addprototype (LexState *ls) {
   Proto *clp;
   lua_State *L = ls->L;
   FuncState *fs = ls->fs;
   Proto *f = fs->f;  /* prototype of current function */
   if (fs->np >= f->sizep) {
     int oldsize = f->sizep;
     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
     while (oldsize < f->sizep)
       f->p[oldsize++] = NULL;
   }
   f->p[fs->np++] = clp = luaF_newproto(L);
   luaC_objbarrier(L, f, clp);
   return clp;
 }
 
 
 /*
 ** codes instruction to create new closure in parent function.
 ** The OP_CLOSURE instruction must use the last available register,
 ** so that, if it invokes the GC, the GC knows which registers
 ** are in use at that time.
 */
 static void codeclosure (LexState *ls, expdesc *v) {
   FuncState *fs = ls->fs->prev;
   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
 }
 
 
 static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
   Proto *f;
   fs->prev = ls->fs;  /* linked list of funcstates */
   fs->ls = ls;
   ls->fs = fs;
   fs->pc = 0;
   fs->lasttarget = 0;
   fs->jpc = NO_JUMP;
   fs->freereg = 0;
   fs->nk = 0;
   fs->np = 0;
   fs->nups = 0;
   fs->nlocvars = 0;
   fs->nactvar = 0;
   fs->firstlocal = ls->dyd->actvar.n;
   fs->bl = NULL;
   f = fs->f;
   f->source = ls->source;
   f->maxstacksize = 2;  /* registers 0/1 are always valid */
   enterblock(fs, bl, 0);
 }
 
 
 static void close_func (LexState *ls) {
   lua_State *L = ls->L;
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
   luaK_ret(fs, 0, 0);  /* final return */
   leaveblock(fs);
   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
   f->sizecode = fs->pc;
   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
   f->sizelineinfo = fs->pc;
   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
   f->sizek = fs->nk;
   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
   f->sizep = fs->np;
   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
   f->sizelocvars = fs->nlocvars;
   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
   f->sizeupvalues = fs->nups;
   lua_assert(fs->bl == NULL);
   ls->fs = fs->prev;
   luaC_checkGC(L);
 }
 
 
 
 /*============================================================*/
 /* GRAMMAR RULES */
 /*============================================================*/
 
 
 /*
 ** check whether current token is in the follow set of a block.
 ** 'until' closes syntactical blocks, but do not close scope,
 ** so it is handled in separate.
 */
 static int block_follow (LexState *ls, int withuntil) {
   switch (ls->t.token) {
     case TK_ELSE: case TK_ELSEIF:
     case TK_END: case TK_EOS:
       return 1;
     case TK_UNTIL: return withuntil;
     default: return 0;
   }
 }
 
 
 static void statlist (LexState *ls) {
   /* statlist -> { stat [';'] } */
   while (!block_follow(ls, 1)) {
     if (ls->t.token == TK_RETURN) {
       statement(ls);
       return;  /* 'return' must be last statement */
     }
     statement(ls);
   }
 }
 
 
 static void fieldsel (LexState *ls, expdesc *v) {
   /* fieldsel -> ['.' | ':'] NAME */
   FuncState *fs = ls->fs;
   expdesc key;
   luaK_exp2anyregup(fs, v);
   luaX_next(ls);  /* skip the dot or colon */
   checkname(ls, &key);
   luaK_indexed(fs, v, &key);
 }
 
 
 static void yindex (LexState *ls, expdesc *v) {
   /* index -> '[' expr ']' */
   luaX_next(ls);  /* skip the '[' */
   expr(ls, v);
   luaK_exp2val(ls->fs, v);
   checknext(ls, ']');
 }
 
 
 /*
 ** {======================================================================
 ** Rules for Constructors
 ** =======================================================================
 */
 
 
 struct ConsControl {
   expdesc v;  /* last list item read */
   expdesc *t;  /* table descriptor */
   int nh;  /* total number of 'record' elements */
   int na;  /* total number of array elements */
   int tostore;  /* number of array elements pending to be stored */
 };
 
 
 static void recfield (LexState *ls, struct ConsControl *cc) {
   /* recfield -> (NAME | '['exp1']') = exp1 */
   FuncState *fs = ls->fs;
   int reg = ls->fs->freereg;
   expdesc key, val;
   int rkkey;
   if (ls->t.token == TK_NAME) {
     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
     checkname(ls, &key);
   }
   else  /* ls->t.token == '[' */
     yindex(ls, &key);
   cc->nh++;
   checknext(ls, '=');
   rkkey = luaK_exp2RK(fs, &key);
   expr(ls, &val);
   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
   fs->freereg = reg;  /* free registers */
 }
 
 
 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
   if (cc->v.k == VVOID) return;  /* there is no list item */
   luaK_exp2nextreg(fs, &cc->v);
   cc->v.k = VVOID;
   if (cc->tostore == LFIELDS_PER_FLUSH) {
     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
     cc->tostore = 0;  /* no more items pending */
   }
 }
 
 
 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
   if (cc->tostore == 0) return;
   if (hasmultret(cc->v.k)) {
     luaK_setmultret(fs, &cc->v);
     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
     cc->na--;  /* do not count last expression (unknown number of elements) */
   }
   else {
     if (cc->v.k != VVOID)
       luaK_exp2nextreg(fs, &cc->v);
     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
   }
 }
 
 
 static void listfield (LexState *ls, struct ConsControl *cc) {
   /* listfield -> exp */
   expr(ls, &cc->v);
   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
   cc->na++;
   cc->tostore++;
 }
 
 
 static void field (LexState *ls, struct ConsControl *cc) {
   /* field -> listfield | recfield */
   switch(ls->t.token) {
     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
       if (luaX_lookahead(ls) != '=')  /* expression? */
         listfield(ls, cc);
       else
         recfield(ls, cc);
       break;
     }
     case '[': {
       recfield(ls, cc);
       break;
     }
     default: {
       listfield(ls, cc);
       break;
     }
   }
 }
 
 
 static void constructor (LexState *ls, expdesc *t) {
   /* constructor -> '{' [ field { sep field } [sep] ] '}'
      sep -> ',' | ';' */
   FuncState *fs = ls->fs;
   int line = ls->linenumber;
   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
   struct ConsControl cc;
   cc.na = cc.nh = cc.tostore = 0;
   cc.t = t;
   init_exp(t, VRELOCABLE, pc);
   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
   checknext(ls, '{');
   do {
     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
     if (ls->t.token == '}') break;
     closelistfield(fs, &cc);
     field(ls, &cc);
   } while (testnext(ls, ',') || testnext(ls, ';'));
   check_match(ls, '}', '{', line);
   lastlistfield(fs, &cc);
   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
 }
 
 /* }====================================================================== */
 
 
 
 static void parlist (LexState *ls) {
   /* parlist -> [ param { ',' param } ] */
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
   int nparams = 0;
   f->is_vararg = 0;
   if (ls->t.token != ')') {  /* is 'parlist' not empty? */
     do {
       switch (ls->t.token) {
         case TK_NAME: {  /* param -> NAME */
           new_localvar(ls, str_checkname(ls));
           nparams++;
           break;
         }
         case TK_DOTS: {  /* param -> '...' */
           luaX_next(ls);
           f->is_vararg = 1;  /* declared vararg */
           break;
         }
         default: luaX_syntaxerror(ls, "<name> or '...' expected");
       }
     } while (!f->is_vararg && testnext(ls, ','));
   }
   adjustlocalvars(ls, nparams);
   f->numparams = cast_byte(fs->nactvar);
   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
 }
 
 
 static void body (LexState *ls, expdesc *e, int ismethod, int line) {
   /* body ->  '(' parlist ')' block END */
   FuncState new_fs;
   BlockCnt bl;
   new_fs.f = addprototype(ls);
   new_fs.f->linedefined = line;
   open_func(ls, &new_fs, &bl);
   checknext(ls, '(');
   if (ismethod) {
     new_localvarliteral(ls, "self");  /* create 'self' parameter */
     adjustlocalvars(ls, 1);
   }
   parlist(ls);
   checknext(ls, ')');
   statlist(ls);
   new_fs.f->lastlinedefined = ls->linenumber;
   check_match(ls, TK_END, TK_FUNCTION, line);
   codeclosure(ls, e);
   close_func(ls);
 }
 
 
 static int explist (LexState *ls, expdesc *v) {
   /* explist -> expr { ',' expr } */
   int n = 1;  /* at least one expression */
   expr(ls, v);
   while (testnext(ls, ',')) {
     luaK_exp2nextreg(ls->fs, v);
     expr(ls, v);
     n++;
   }
   return n;
 }
 
 
 static void funcargs (LexState *ls, expdesc *f, int line) {
   FuncState *fs = ls->fs;
   expdesc args;
   int base, nparams;
   switch (ls->t.token) {
     case '(': {  /* funcargs -> '(' [ explist ] ')' */
       luaX_next(ls);
       if (ls->t.token == ')')  /* arg list is empty? */
         args.k = VVOID;
       else {
         explist(ls, &args);
         luaK_setmultret(fs, &args);
       }
       check_match(ls, ')', '(', line);
       break;
     }
     case '{': {  /* funcargs -> constructor */
       constructor(ls, &args);
       break;
     }
     case TK_STRING: {  /* funcargs -> STRING */
       codestring(ls, &args, ls->t.seminfo.ts);
       luaX_next(ls);  /* must use 'seminfo' before 'next' */
       break;
     }
     default: {
       luaX_syntaxerror(ls, "function arguments expected");
     }
   }
   lua_assert(f->k == VNONRELOC);
   base = f->u.info;  /* base register for call */
   if (hasmultret(args.k))
     nparams = LUA_MULTRET;  /* open call */
   else {
     if (args.k != VVOID)
       luaK_exp2nextreg(fs, &args);  /* close last argument */
     nparams = fs->freereg - (base+1);
   }
   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
   luaK_fixline(fs, line);
   fs->freereg = base+1;  /* call remove function and arguments and leaves
                             (unless changed) one result */
 }
 
 
 
 
 /*
 ** {======================================================================
 ** Expression parsing
 ** =======================================================================
 */
 
 
 static void primaryexp (LexState *ls, expdesc *v) {
   /* primaryexp -> NAME | '(' expr ')' */
   switch (ls->t.token) {
     case '(': {
       int line = ls->linenumber;
       luaX_next(ls);
       expr(ls, v);
       check_match(ls, ')', '(', line);
       luaK_dischargevars(ls->fs, v);
       return;
     }
     case TK_NAME: {
       singlevar(ls, v);
       return;
     }
     default: {
       luaX_syntaxerror(ls, "unexpected symbol");
     }
   }
 }
 
 
 static void suffixedexp (LexState *ls, expdesc *v) {
   /* suffixedexp ->
        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
   FuncState *fs = ls->fs;
   int line = ls->linenumber;
   primaryexp(ls, v);
   for (;;) {
     switch (ls->t.token) {
       case '.': {  /* fieldsel */
         fieldsel(ls, v);
         break;
       }
       case '[': {  /* '[' exp1 ']' */
         expdesc key;
         luaK_exp2anyregup(fs, v);
         yindex(ls, &key);
         luaK_indexed(fs, v, &key);
         break;
       }
       case ':': {  /* ':' NAME funcargs */
         expdesc key;
         luaX_next(ls);
         checkname(ls, &key);
         luaK_self(fs, v, &key);
         funcargs(ls, v, line);
         break;
       }
       case '(': case TK_STRING: case '{': {  /* funcargs */
         luaK_exp2nextreg(fs, v);
         funcargs(ls, v, line);
         break;
       }
       default: return;
     }
   }
 }
 
 
 static void simpleexp (LexState *ls, expdesc *v) {
   /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
                   constructor | FUNCTION body | suffixedexp */
   switch (ls->t.token) {
     case TK_FLT: {
       init_exp(v, VKFLT, 0);
       v->u.nval = ls->t.seminfo.r;
       break;
     }
     case TK_INT: {
       init_exp(v, VKINT, 0);
       v->u.ival = ls->t.seminfo.i;
       break;
     }
     case TK_STRING: {
       codestring(ls, v, ls->t.seminfo.ts);
       break;
     }
     case TK_NIL: {
       init_exp(v, VNIL, 0);
       break;
     }
     case TK_TRUE: {
       init_exp(v, VTRUE, 0);
       break;
     }
     case TK_FALSE: {
       init_exp(v, VFALSE, 0);
       break;
     }
     case TK_DOTS: {  /* vararg */
       FuncState *fs = ls->fs;
       check_condition(ls, fs->f->is_vararg,
                       "cannot use '...' outside a vararg function");
       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
       break;
     }
     case '{': {  /* constructor */
       constructor(ls, v);
       return;
     }
     case TK_FUNCTION: {
       luaX_next(ls);
       body(ls, v, 0, ls->linenumber);
       return;
     }
     default: {
       suffixedexp(ls, v);
       return;
     }
   }
   luaX_next(ls);
 }
 
 
 static UnOpr getunopr (int op) {
   switch (op) {
     case TK_NOT: return OPR_NOT;
     case '-': return OPR_MINUS;
     case '~': return OPR_BNOT;
     case '#': return OPR_LEN;
     default: return OPR_NOUNOPR;
   }
 }
 
 
 static BinOpr getbinopr (int op) {
   switch (op) {
     case '+': return OPR_ADD;
     case '-': return OPR_SUB;
     case '*': return OPR_MUL;
     case '%': return OPR_MOD;
     case '^': return OPR_POW;
     case '/': return OPR_DIV;
     case TK_IDIV: return OPR_IDIV;
     case '&': return OPR_BAND;
     case '|': return OPR_BOR;
     case '~': return OPR_BXOR;
     case TK_SHL: return OPR_SHL;
     case TK_SHR: return OPR_SHR;
     case TK_CONCAT: return OPR_CONCAT;
     case TK_NE: return OPR_NE;
     case TK_EQ: return OPR_EQ;
     case '<': return OPR_LT;
     case TK_LE: return OPR_LE;
     case '>': return OPR_GT;
     case TK_GE: return OPR_GE;
     case TK_AND: return OPR_AND;
     case TK_OR: return OPR_OR;
     default: return OPR_NOBINOPR;
   }
 }
 
 
 static const struct {
   lu_byte left;  /* left priority for each binary operator */
   lu_byte right; /* right priority */
 } priority[] = {  /* ORDER OPR */
    {10, 10}, {10, 10},           /* '+' '-' */
    {11, 11}, {11, 11},           /* '*' '%' */
    {14, 13},                  /* '^' (right associative) */
    {11, 11}, {11, 11},           /* '/' '//' */
    {6, 6}, {4, 4}, {5, 5},   /* '&' '|' '~' */
    {7, 7}, {7, 7},           /* '<<' '>>' */
    {9, 8},                   /* '..' (right associative) */
    {3, 3}, {3, 3}, {3, 3},   /* ==, <, <= */
    {3, 3}, {3, 3}, {3, 3},   /* ~=, >, >= */
    {2, 2}, {1, 1}            /* and, or */
 };
 
 #define UNARY_PRIORITY	12  /* priority for unary operators */
 
 
 /*
 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
 ** where 'binop' is any binary operator with a priority higher than 'limit'
 */
 static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
   BinOpr op;
   UnOpr uop;
   enterlevel(ls);
   uop = getunopr(ls->t.token);
   if (uop != OPR_NOUNOPR) {
     int line = ls->linenumber;
     luaX_next(ls);
     subexpr(ls, v, UNARY_PRIORITY);
     luaK_prefix(ls->fs, uop, v, line);
   }
   else simpleexp(ls, v);
   /* expand while operators have priorities higher than 'limit' */
   op = getbinopr(ls->t.token);
   while (op != OPR_NOBINOPR && priority[op].left > limit) {
     expdesc v2;
     BinOpr nextop;
     int line = ls->linenumber;
     luaX_next(ls);
     luaK_infix(ls->fs, op, v);
     /* read sub-expression with higher priority */
     nextop = subexpr(ls, &v2, priority[op].right);
     luaK_posfix(ls->fs, op, v, &v2, line);
     op = nextop;
   }
   leavelevel(ls);
   return op;  /* return first untreated operator */
 }
 
 
 static void expr (LexState *ls, expdesc *v) {
   subexpr(ls, v, 0);
 }
 
 /* }==================================================================== */
 
 
 
 /*
 ** {======================================================================
 ** Rules for Statements
 ** =======================================================================
 */
 
 
 static void block (LexState *ls) {
   /* block -> statlist */
   FuncState *fs = ls->fs;
   BlockCnt bl;
   enterblock(fs, &bl, 0);
   statlist(ls);
   leaveblock(fs);
 }
 
 
 /*
 ** structure to chain all variables in the left-hand side of an
 ** assignment
 */
 struct LHS_assign {
   struct LHS_assign *prev;
   expdesc v;  /* variable (global, local, upvalue, or indexed) */
 };
 
 
 /*
 ** check whether, in an assignment to an upvalue/local variable, the
 ** upvalue/local variable is begin used in a previous assignment to a
 ** table. If so, save original upvalue/local value in a safe place and
 ** use this safe copy in the previous assignment.
 */
 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
   FuncState *fs = ls->fs;
   int extra = fs->freereg;  /* eventual position to save local variable */
   int conflict = 0;
   for (; lh; lh = lh->prev) {  /* check all previous assignments */
     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
       /* table is the upvalue/local being assigned now? */
       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
         conflict = 1;
         lh->v.u.ind.vt = VLOCAL;
         lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
       }
       /* index is the local being assigned? (index cannot be upvalue) */
       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
         conflict = 1;
         lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
       }
     }
   }
   if (conflict) {
     /* copy upvalue/local value to a temporary (in position 'extra') */
     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
     luaK_codeABC(fs, op, extra, v->u.info, 0);
     luaK_reserveregs(fs, 1);
   }
 }
 
 
 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
   expdesc e;
   check_condition(ls, vkisvar(lh->v.k), "syntax error");
   if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
     struct LHS_assign nv;
     nv.prev = lh;
     suffixedexp(ls, &nv.v);
     if (nv.v.k != VINDEXED)
       check_conflict(ls, lh, &nv.v);
     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
                     "C levels");
     assignment(ls, &nv, nvars+1);
   }
   else {  /* assignment -> '=' explist */
     int nexps;
     checknext(ls, '=');
     nexps = explist(ls, &e);
     if (nexps != nvars)
       adjust_assign(ls, nvars, nexps, &e);
     else {
       luaK_setoneret(ls->fs, &e);  /* close last expression */
       luaK_storevar(ls->fs, &lh->v, &e);
       return;  /* avoid default */
     }
   }
   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
   luaK_storevar(ls->fs, &lh->v, &e);
 }
 
 
 static int cond (LexState *ls) {
   /* cond -> exp */
   expdesc v;
   expr(ls, &v);  /* read condition */
   if (v.k == VNIL) v.k = VFALSE;  /* 'falses' are all equal here */
   luaK_goiftrue(ls->fs, &v);
   return v.f;
 }
 
 
 static void gotostat (LexState *ls, int pc) {
   int line = ls->linenumber;
   TString *label;
   int g;
   if (testnext(ls, TK_GOTO))
     label = str_checkname(ls);
   else {
     luaX_next(ls);  /* skip break */
     label = luaS_new(ls->L, "break");
   }
   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
   findlabel(ls, g);  /* close it if label already defined */
 }
 
 
 /* check for repeated labels on the same block */
 static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
   int i;
   for (i = fs->bl->firstlabel; i < ll->n; i++) {
     if (eqstr(label, ll->arr[i].name)) {
       const char *msg = luaO_pushfstring(fs->ls->L,
                           "label '%s' already defined on line %d",
                           getstr(label), ll->arr[i].line);
       semerror(fs->ls, msg);
     }
   }
 }
 
 
 /* skip no-op statements */
 static void skipnoopstat (LexState *ls) {
   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
     statement(ls);
 }
 
 
 static void labelstat (LexState *ls, TString *label, int line) {
   /* label -> '::' NAME '::' */
   FuncState *fs = ls->fs;
   Labellist *ll = &ls->dyd->label;
   int l;  /* index of new label being created */
   checkrepeated(fs, ll, label);  /* check for repeated labels */
   checknext(ls, TK_DBCOLON);  /* skip double colon */
   /* create new entry for this label */
   l = newlabelentry(ls, ll, label, line, luaK_getlabel(fs));
   skipnoopstat(ls);  /* skip other no-op statements */
   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
     /* assume that locals are already out of scope */
     ll->arr[l].nactvar = fs->bl->nactvar;
   }
   findgotos(ls, &ll->arr[l]);
 }
 
 
 static void whilestat (LexState *ls, int line) {
   /* whilestat -> WHILE cond DO block END */
   FuncState *fs = ls->fs;
   int whileinit;
   int condexit;
   BlockCnt bl;
   luaX_next(ls);  /* skip WHILE */
   whileinit = luaK_getlabel(fs);
   condexit = cond(ls);
   enterblock(fs, &bl, 1);
   checknext(ls, TK_DO);
   block(ls);
   luaK_jumpto(fs, whileinit);
   check_match(ls, TK_END, TK_WHILE, line);
   leaveblock(fs);
   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
 }
 
 
 static void repeatstat (LexState *ls, int line) {
   /* repeatstat -> REPEAT block UNTIL cond */
   int condexit;
   FuncState *fs = ls->fs;
   int repeat_init = luaK_getlabel(fs);
   BlockCnt bl1, bl2;
   enterblock(fs, &bl1, 1);  /* loop block */
   enterblock(fs, &bl2, 0);  /* scope block */
   luaX_next(ls);  /* skip REPEAT */
   statlist(ls);
   check_match(ls, TK_UNTIL, TK_REPEAT, line);
   condexit = cond(ls);  /* read condition (inside scope block) */
   if (bl2.upval)  /* upvalues? */
     luaK_patchclose(fs, condexit, bl2.nactvar);
   leaveblock(fs);  /* finish scope */
   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
   leaveblock(fs);  /* finish loop */
 }
 
 
 static int exp1 (LexState *ls) {
   expdesc e;
   int reg;
   expr(ls, &e);
   luaK_exp2nextreg(ls->fs, &e);
   lua_assert(e.k == VNONRELOC);
   reg = e.u.info;
   return reg;
 }
 
 
 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
   /* forbody -> DO block */
   BlockCnt bl;
   FuncState *fs = ls->fs;
   int prep, endfor;
   adjustlocalvars(ls, 3);  /* control variables */
   checknext(ls, TK_DO);
   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
   enterblock(fs, &bl, 0);  /* scope for declared variables */
   adjustlocalvars(ls, nvars);
   luaK_reserveregs(fs, nvars);
   block(ls);
   leaveblock(fs);  /* end of scope for declared variables */
   luaK_patchtohere(fs, prep);
   if (isnum)  /* numeric for? */
     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
   else {  /* generic for */
     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
     luaK_fixline(fs, line);
     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
   }
   luaK_patchlist(fs, endfor, prep + 1);
   luaK_fixline(fs, line);
 }
 
 
 static void fornum (LexState *ls, TString *varname, int line) {
   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
   FuncState *fs = ls->fs;
   int base = fs->freereg;
   new_localvarliteral(ls, "(for index)");
   new_localvarliteral(ls, "(for limit)");
   new_localvarliteral(ls, "(for step)");
   new_localvar(ls, varname);
   checknext(ls, '=');
   exp1(ls);  /* initial value */
   checknext(ls, ',');
   exp1(ls);  /* limit */
   if (testnext(ls, ','))
     exp1(ls);  /* optional step */
   else {  /* default step = 1 */
     luaK_codek(fs, fs->freereg, luaK_intK(fs, 1));
     luaK_reserveregs(fs, 1);
   }
   forbody(ls, base, line, 1, 1);
 }
 
 
 static void forlist (LexState *ls, TString *indexname) {
   /* forlist -> NAME {,NAME} IN explist forbody */
   FuncState *fs = ls->fs;
   expdesc e;
   int nvars = 4;  /* gen, state, control, plus at least one declared var */
   int line;
   int base = fs->freereg;
   /* create control variables */
   new_localvarliteral(ls, "(for generator)");
   new_localvarliteral(ls, "(for state)");
   new_localvarliteral(ls, "(for control)");
   /* create declared variables */
   new_localvar(ls, indexname);
   while (testnext(ls, ',')) {
     new_localvar(ls, str_checkname(ls));
     nvars++;
   }
   checknext(ls, TK_IN);
   line = ls->linenumber;
   adjust_assign(ls, 3, explist(ls, &e), &e);
   luaK_checkstack(fs, 3);  /* extra space to call generator */
   forbody(ls, base, line, nvars - 3, 0);
 }
 
 
 static void forstat (LexState *ls, int line) {
   /* forstat -> FOR (fornum | forlist) END */
   FuncState *fs = ls->fs;
   TString *varname;
   BlockCnt bl;
   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
   luaX_next(ls);  /* skip 'for' */
   varname = str_checkname(ls);  /* first variable name */
   switch (ls->t.token) {
     case '=': fornum(ls, varname, line); break;
     case ',': case TK_IN: forlist(ls, varname); break;
     default: luaX_syntaxerror(ls, "'=' or 'in' expected");
   }
   check_match(ls, TK_END, TK_FOR, line);
   leaveblock(fs);  /* loop scope ('break' jumps to this point) */
 }
 
 
 static void test_then_block (LexState *ls, int *escapelist) {
   /* test_then_block -> [IF | ELSEIF] cond THEN block */
   BlockCnt bl;
   FuncState *fs = ls->fs;
   expdesc v;
   int jf;  /* instruction to skip 'then' code (if condition is false) */
   luaX_next(ls);  /* skip IF or ELSEIF */
   expr(ls, &v);  /* read condition */
   checknext(ls, TK_THEN);
   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
     gotostat(ls, v.t);  /* handle goto/break */
     while (testnext(ls, ';')) {}  /* skip colons */
     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
       leaveblock(fs);
       return;  /* and that is it */
     }
     else  /* must skip over 'then' part if condition is false */
       jf = luaK_jump(fs);
   }
   else {  /* regular case (not goto/break) */
     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
     enterblock(fs, &bl, 0);
     jf = v.f;
   }
   statlist(ls);  /* 'then' part */
   leaveblock(fs);
   if (ls->t.token == TK_ELSE ||
       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
   luaK_patchtohere(fs, jf);
 }
 
 
 static void ifstat (LexState *ls, int line) {
   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
   FuncState *fs = ls->fs;
   int escapelist = NO_JUMP;  /* exit list for finished parts */
   test_then_block(ls, &escapelist);  /* IF cond THEN block */
   while (ls->t.token == TK_ELSEIF)
     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
   if (testnext(ls, TK_ELSE))
     block(ls);  /* 'else' part */
   check_match(ls, TK_END, TK_IF, line);
   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
 }
 
 
 static void localfunc (LexState *ls) {
   expdesc b;
   FuncState *fs = ls->fs;
   new_localvar(ls, str_checkname(ls));  /* new local variable */
   adjustlocalvars(ls, 1);  /* enter its scope */
   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
   /* debug information will only see the variable after this point! */
   getlocvar(fs, b.u.info)->startpc = fs->pc;
 }
 
 
 static void localstat (LexState *ls) {
   /* stat -> LOCAL NAME {',' NAME} ['=' explist] */
   int nvars = 0;
   int nexps;
   expdesc e;
   do {
     new_localvar(ls, str_checkname(ls));
     nvars++;
   } while (testnext(ls, ','));
   if (testnext(ls, '='))
     nexps = explist(ls, &e);
   else {
     e.k = VVOID;
     nexps = 0;
   }
   adjust_assign(ls, nvars, nexps, &e);
   adjustlocalvars(ls, nvars);
 }
 
 
 static int funcname (LexState *ls, expdesc *v) {
   /* funcname -> NAME {fieldsel} [':' NAME] */
   int ismethod = 0;
   singlevar(ls, v);
   while (ls->t.token == '.')
     fieldsel(ls, v);
   if (ls->t.token == ':') {
     ismethod = 1;
     fieldsel(ls, v);
   }
   return ismethod;
 }
 
 
 static void funcstat (LexState *ls, int line) {
   /* funcstat -> FUNCTION funcname body */
   int ismethod;
   expdesc v, b;
   luaX_next(ls);  /* skip FUNCTION */
   ismethod = funcname(ls, &v);
   body(ls, &b, ismethod, line);
   luaK_storevar(ls->fs, &v, &b);
   luaK_fixline(ls->fs, line);  /* definition "happens" in the first line */
 }
 
 
 static void exprstat (LexState *ls) {
   /* stat -> func | assignment */
   FuncState *fs = ls->fs;
   struct LHS_assign v;
   suffixedexp(ls, &v.v);
   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
     v.prev = NULL;
     assignment(ls, &v, 1);
   }
   else {  /* stat -> func */
     check_condition(ls, v.v.k == VCALL, "syntax error");
     SETARG_C(getinstruction(fs, &v.v), 1);  /* call statement uses no results */
   }
 }
 
 
 static void retstat (LexState *ls) {
   /* stat -> RETURN [explist] [';'] */
   FuncState *fs = ls->fs;
   expdesc e;
   int first, nret;  /* registers with returned values */
   if (block_follow(ls, 1) || ls->t.token == ';')
     first = nret = 0;  /* return no values */
   else {
     nret = explist(ls, &e);  /* optional return values */
     if (hasmultret(e.k)) {
       luaK_setmultret(fs, &e);
       if (e.k == VCALL && nret == 1) {  /* tail call? */
         SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
         lua_assert(GETARG_A(getinstruction(fs,&e)) == fs->nactvar);
       }
       first = fs->nactvar;
       nret = LUA_MULTRET;  /* return all values */
     }
     else {
       if (nret == 1)  /* only one single value? */
         first = luaK_exp2anyreg(fs, &e);
       else {
         luaK_exp2nextreg(fs, &e);  /* values must go to the stack */
         first = fs->nactvar;  /* return all active values */
         lua_assert(nret == fs->freereg - first);
       }
     }
   }
   luaK_ret(fs, first, nret);
   testnext(ls, ';');  /* skip optional semicolon */
 }
 
 
 static void statement (LexState *ls) {
   int line = ls->linenumber;  /* may be needed for error messages */
   enterlevel(ls);
   switch (ls->t.token) {
     case ';': {  /* stat -> ';' (empty statement) */
       luaX_next(ls);  /* skip ';' */
       break;
     }
     case TK_IF: {  /* stat -> ifstat */
       ifstat(ls, line);
       break;
     }
     case TK_WHILE: {  /* stat -> whilestat */
       whilestat(ls, line);
       break;
     }
     case TK_DO: {  /* stat -> DO block END */
       luaX_next(ls);  /* skip DO */
       block(ls);
       check_match(ls, TK_END, TK_DO, line);
       break;
     }
     case TK_FOR: {  /* stat -> forstat */
       forstat(ls, line);
       break;
     }
     case TK_REPEAT: {  /* stat -> repeatstat */
       repeatstat(ls, line);
       break;
     }
     case TK_FUNCTION: {  /* stat -> funcstat */
       funcstat(ls, line);
       break;
     }
     case TK_LOCAL: {  /* stat -> localstat */
       luaX_next(ls);  /* skip LOCAL */
       if (testnext(ls, TK_FUNCTION))  /* local function? */
         localfunc(ls);
       else
         localstat(ls);
       break;
     }
     case TK_DBCOLON: {  /* stat -> label */
       luaX_next(ls);  /* skip double colon */
       labelstat(ls, str_checkname(ls), line);
       break;
     }
     case TK_RETURN: {  /* stat -> retstat */
       luaX_next(ls);  /* skip RETURN */
       retstat(ls);
       break;
     }
     case TK_BREAK:   /* stat -> breakstat */
     case TK_GOTO: {  /* stat -> 'goto' NAME */
       gotostat(ls, luaK_jump(ls->fs));
       break;
     }
     default: {  /* stat -> func | assignment */
       exprstat(ls);
       break;
     }
   }
   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
              ls->fs->freereg >= ls->fs->nactvar);
   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
   leavelevel(ls);
 }
 
 /* }====================================================================== */
 
 
 /*
 ** compiles the main function, which is a regular vararg function with an
 ** upvalue named LUA_ENV
 */
 static void mainfunc (LexState *ls, FuncState *fs) {
   BlockCnt bl;
   expdesc v;
   open_func(ls, fs, &bl);
   fs->f->is_vararg = 1;  /* main function is always declared vararg */
   init_exp(&v, VLOCAL, 0);  /* create and... */
   newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
   luaX_next(ls);  /* read first token */
   statlist(ls);  /* parse main body */
   check(ls, TK_EOS);
   close_func(ls);
 }
 
 
 LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
                        Dyndata *dyd, const char *name, int firstchar) {
   LexState lexstate;
   FuncState funcstate;
   LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
   setclLvalue(L, L->top, cl);  /* anchor it (to avoid being collected) */
   luaD_inctop(L);
   lexstate.h = luaH_new(L);  /* create table for scanner */
   sethvalue(L, L->top, lexstate.h);  /* anchor it */
   luaD_inctop(L);
   funcstate.f = cl->p = luaF_newproto(L);
   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
   lua_assert(iswhite(funcstate.f));  /* do not need barrier here */
   lexstate.buff = buff;
   lexstate.dyd = dyd;
   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
   mainfunc(&lexstate, &funcstate);
   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
   /* all scopes should be correctly finished */
   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
   L->top--;  /* remove scanner's table */
   return cl;  /* closure is on the stack, too */
 }